Abstract In present work, nickel pyrophosphate (Ni2P2O7.8H2O) thin film on stainless steel substrate synthesized using facile chemical bath deposition method and used as cathode electrode for asymmetric supercapacitor. Three compositions of nickel phosphate with varying of nickel:phosphate (2:1, 1:1 and 1:2) molar ratio are prepared to study composition effect on microstructure and subsequently on supercapacitive performance. Morphology changes with composition from microflower to leaf like, consequently supercapacitive performance influences with increasing phosphate content in material. The well dispersed leaf like microstructure (nickel:phosphate;1:2) of nickel pyrophosphate offers more active sites and it shows maximum specific capacitance of 482 F g−1 at current density of 3 mA cm-2 along with 99.73% capacitive retention over 2500 cycles. Moreover, an asymmetric device fabricated using nickel pyrophosphate and reduced graphene oxide as a positive and negative electrode, respectively. Prepared asymmetric supercapacitor offers specific capacitance of 74.81 F g-1 at 0.9 mA cm-2 current density with 26.6 Wh kg-1 energy density at a moderately high power density of 870.6 W kg-1. Also, exhibits 87.35% of capacitive retention over 5500 cycles at 4 mA cm-2 current density.

中文翻译：

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焦磷酸镍等调节微叶作为非对称超级电容器的阴极

摘要 在目前的工作中，焦磷酸镍 (Ni2P2O7.8H2O) 薄膜在不锈钢基板上使用简便的化学浴沉积法合成，用作非对称超级电容器的阴极。制备了三种不同镍:磷酸盐（2:1、1:1 和 1:2）摩尔比的磷酸镍组合物，以研究组合物对微观结构的影响，进而研究其对超级电容性能的影响。形态随成分从微花变为叶状，因此随着材料中磷酸盐含量的增加，超级电容性能会产生影响。焦磷酸镍良好分散的叶状微结构（镍：磷酸盐；1：2）提供了更多的活性位点，并且在 3 mA cm-2 的电流密度下显示出 482 F g-1 的最大比电容以及 99.73% 的电容保持率2500 次循环。此外，分别使用焦磷酸镍和还原氧化石墨烯作为正极和负极制造的不对称器件。制备的非对称超级电容器在 0.9 mA cm-2 电流密度下提供 74.81 F g-1 的比电容，在 870.6 W kg-1 的中等高功率密度下提供 26.6 Wh kg-1 能量密度。此外，在 4 mA cm-2 电流密度下，在 5500 次循环中显示出 87.35% 的电容保持率。